The Frequency Formula is a single side tank with 9 notes, tuned in our arrangement of the F# Major scale and calibrated to A=430hz. The frequencies of this drum encompass a plethora of sonic geometry, like Pythagoras and Beethoven collaborating with Mother Nature. The examples of this phenomena included in this drum are as follows.. the Triangle (F#3/180hz), Square+Circle (F#4/360hz), Pentagon (C#5/540hz), an octave of a Septagon (A#4/450hz), and even an octave of Phi, the Golden Number (E4/323hz). To be more clear, the degrees of the angles of these shapes is the same as the frequency of these notes (a circle=360 degrees / F#3 = 360hz). To understand this concept in more depth, please refer to the video in this link – Sonic Geometry. This video claims these correlation’s happen when A=432hz, but they are even more accurately paralleled when A=430hz, which is how the Frequency Formula is tuned/calibrated. You can also choose to have this drum expanded into a double side drum, which will then contain the higher octaves of each of the shapes/notes on the top of the drum AND also will contain a Septagon (A#5/900hz), and an Octagon (C#6/1080hz)! Contact me for this option..